The xylem transports water and minerals from the roots up the plant stem and into the leaves.
In a mature flowering plant or tree, most of the cells that make up the xylem are specialised cells called vessels. Vessels:
Transport in the xylem is a physical process. It does not require energy.
Phloem moves sugar that the plant has produced by photosynthesis to where it is needed for processes such as:
Transport in the phloem is therefore both up and down the stem. Transport of substances in the phloem is called translocation.
Phloem consists of living cells. The cells that make up the phloem are adapted to their function:
|Type of transport||Physical process||Requires energy|
|Substances transported||Water and minerals||Products of photosynthesis, including sugars and amino acids dissolved in water|
|Direction of transport||Upwards||Upwards and downwards|
The xylem and phloem are distributed differently in roots and stems. In the root, the xylem forms a central column, forming a solid support. The phloem is towards the centre, outside the xylem.
In the stem, the transport tissues of the xylem and phloem are grouped into vascular bundles.